1. Field of the Invention.
This invention relates, in general, to a prefabricated door frame kit designed for easy shipping, handling, storage, and installation. More specifically, this invention relates to prefabricated door frames constructed to self-align to fit out-of-plumb walls, warped doors, or varying wall thicknesses, while minimizing separation of joints.
2. Description of the Related Art.
Prefabricated door assemblies have been built in order to eliminate the need for skilled craftsmen to custom-build door frame and door systems at construction sites. Unitary construction of these prefabricated door assemblies has proved cumbersome, inefficient to ship, and difficult to install into imperfect roughed-in framing. Sklar (U.S. Pat. Nos. 3,250,049 and 3,338,008) and J. H. Parker (U.S. Pat. No. 3,239,978) disclose knock-down prefabricated door assemblies, which are relatively easy to transport to construction sites and which fit into openings that vary somewhat in size and shape. McKann (U.S. Pat. No. 5,345,722) discloses a plastic door frame, with first and second inside sections having a frictionally-engaging slot and tongue system for adjustment to varying wall thicknesses. Winston (U.S. Pat. No. 5,365,708) discloses jambs comprising two members, having L-shaped shoulders, which fit together to allow expansion of the jamb width.
G.L. Barr (U.S. Pat. No. 4,166,346) adds to a prefabricated door assembly refinements intended to maintain the tightness and integrity of the joints and of the connection of the door assembly to the door frame. Barr discloses tongue and groove connection of casings to jambs, and a connection between side and head jambs that provides an outward-biasing of the side jambs.
What is still needed is a prefabricated door frame assembly designed for easy installation that results in high quality appearance and tight-fitting joints, in spite of imperfections and irregularities in the rough-framing, jambs, or door.